They are both the same app, it's just that the bbw4 does the extra step of writing the file from RAM to wav.

Flow chart:
Old Way Create file to RAM
New Way Play direct from hard drive





So on the bottom is the RT source file with all the chords that were played, Biab chooses the sections it wants to play from the source file and plays them back in linear order on it's timeline direct from hard drive.
FULL SCREEN